Understanding an organism's response to stress is a fundamental problem in biology. The unifying theme in the stress response is that perturbation of the environment leads to rapid and specific activation of gene expression. In the course of evolution, plants have developed effective mechanisms for resistance to a variety of stresses. Specific induction in gene expression occurs in response to environmental stresses such as infection and wounding; the "immune response" of plants. A major goal of this proposal is to understand the molecular and cellular basis of a plants response to these stresses. Molecular and genetic approaches will be combined to dissect the mechanisms controlling the induction and expression of stress-regulated genes in a model plant system. The dicotyledonous plant Arabidopsis thaliana is ideally suited for such studies; the major advantage is that it is amenable to molecular genetic manipulations common to yeast and Drosophlia but impractical for other higher plants. The long term goal of this project is to ascertain the molecular events involved in signalling and recognition of stress. The action of stress-induced hormones is of fundamental importance in understanding these processes. This research aims to isolate and characterize mutations in genes that affect the biosynthesis, recognition and response to stress-induced ethylene and oligosaccharins and also to define the DNA sequences in stress- induced plant defense response genes which are essential for regulation by these plant stress hormones. Specifically this project aims: 1) to identify and characterize Arabidopsis mutants that are affected in the stress response to exogenous and endogenous oligosaccharide fragments; 2) to identify and "stress ethylene"; 3) to analyze the DNA controlling elements that regulate ethylene- and oligosaccharin-induced genes; 4) to use both genetic and molecular techniques to identify genes/proteins that directly or indirectly mediate the induction of ethylene- and oligosaccharin-regulated genes and 5) to construct and characterize "mutations" in genes regulated by ethylene and oligosaccharins by expression of antisense and sense RNAs for these genes.